Appearance: White needle crystal or crystalline powder Assay: 99.50% min Clarity of Solution: Colourless and clear Loss and Drying: 0.2% max Heavy Metal (as Pb): 0.001% max As 0.0002% max Residue on Ignition: 0.1% max Chloride (as Cl): 0.01% max Sulphate (as SO4): 0.01% Ammonium Salt: 0.02% max Easily Carbonized Matter: Colorless